Motor-powered shaver with pivotally mounted cutter assembly



April 3, 1962 D. E. FRITH 3,027,635

MOTOR-POWERED SHAVER WITH PIVOTALLY MOUNTED CUTTER ASSEMBLY Filed June :5, 1959 2 Sheets-Sheet 1 "i W: I a-a IIIIII I IIIIIIIIIIIII +1417 D. E. FRITH April 3, 1962 MOTOR-POWERED SHAVER WITH PIVOTALLY MOUNTED CUTTER ASSEMBLY 2 Sheets-Sheet 2 Filed June 3, 1959 United States Patent ()fitice 3,027,635 Patented Apr. 3, 1962 3,027,635 MOTOR-POWERED SHAVER WITH PIVOTALLY MOUNTED CUTTER ASSEMBLY Donald E. Frith, 1109 W. Clark, Champaign, Ill. Filed June 3, 1959, Ser. No. 817,882 4 Claims. (Cl. 30-43) This invention relates to an improvement in dry shavers. It is more particularly concerned with an improved shearing head employing a rotating helical cutting blade cooperating with a freely rotatable shear head.

In conventional dry shavers wherein a cutter element is moved at a high speed relative to an outer shear plate the beard stubble is removed by a shearing action effected by a rapid reciprocative motion of the blades of the cutter element. The cutting action of a reciprocating cutter blade produces a nibbling action on the beard stubble which requires that the cutter head be moved back and forth over the skin a number of times with such pressure as to induce an irritation of the skin. The instant invention is concerned with a cutter head for a dry shaver which can be passed back and forth over the face with such facility as to avoid producing any skin irritation from the constant rubbing of the cutter head against the face. By employing a freely rotatable outer shear tube suitably perforated to permit the beard stubble to be eased into the perforations cooperating with a helical cutter blade coaxially mounted within the shear tube there is produced a cutting head for a dry shaver which slices the beard stubble cleanly close to the hair follicle instead of employing the chopping or nibbling action of conventional reciprocating cutter heads. Because the helical cutting blade continuously rotates in the same direction there is no Wasted transfer of power from the drive means to the driven cutter blade. The combination of a perforated, freely rotatable shear tube and a coaxially mounted helical cutting blade provides a dry shaver cutting head which gives a shaving action that is similar to that experienced in the use of a conventional straight edge razor.

In the drawings, FIGURE 1 illustrates a preferred embodiment of the dry shaver head of this invention in which a conical, freely rotatable, outer shear tube is employed.

FIGURE 2 is an enlarged, longitudinal cross-sectional view of the embodiment shown in FIGURE 1 with a fragmentary view of the motor housing.

FIGURE 3 is a transverse cross-sectional view of FIG- URE 2. taken along line 3--3.

FIGURE 4 is a transverse cross-sectional view of FIG- URE 2 taken along line 4-4.

FIGURE 5 is a transverse cross-sectional view of FIG- URE 2 taken along line 55.

FIGURE 6 is an enlarged cross-sectional view of another embodiment of the instant invention in which a cylindrical, shear tube is employed which is pivotally mounted to the motor housing of the dry shaver.

FIGURE 7 is an enlarged cross-sectional view of still another embodiment of the instant invention wherein a plurality of cutting elements are utilized in the cutting head.

FIGURE 8 is a transverse cross-sectional view of FIG- URE 7 taken along line 3--8.

FIGURE 9 is a transverse cross-sectional view of FIG- URE 8 taken along line 9-9.

The preferred embodiment shown in FIGURE 1 comprises a motor housing 10 enclosing a suitable drive means such as an electric motor 11 powered by electricity supplied through electrical leads 12 entering at the rear of housing 10. A flexible sleeve 13 fabricated from a natural or synthetic elastomeric material having a sufiicient rigidity to resist deformation under normal use but flexible enough to permit the free ends thereof to yield to permit rotating collar 14 to be installed thereon is secured to housing 10 by mounting the lip of sleeve 13 in an annular groove provided in the neck portion of housing 10. Flexible sleeve 13 at its free end is provided with an inwardly directed peripheral groove 15 to which the cutter assembly is attached. In peripheral groove 15 is installed an expanding metal clip 16 which cooperates with locking ring 17 to hold rotating collar 14 in place by engaging with a cooperating peripheral groove 18 provided in the inner wall of the recessed portion of rotating collar 14. Clip 16 also provides an anti-friction bearing surface upon which locking ring 17 rotates. The cutter assembly 19 comprises a cutter head 25 and a perforated removable shear tube 2i) is provided with a friction fastening consisting of a band 21 attached to the marginal edge of the open end of shear tube 26 and a retaining ring 22 which rests within the opposed peripheral grooves 23 and 24 provided respectively in the outer face of rotating collar 14 and inner surface of band 21. With this illustrative assembly shear tube 26 is freely rotatable with respect to housing 10. However shear tube 20 is integrally aftixed to rotating collar 14 and does not rotate relative thereto. If desired other anti-friction mountings employing roller bearings, ball bearings, etc. can be used to rotatably mount shear tube Zti in the cutter assembly 19.

As shown the cutter head 25 consists of a frusto-conical base element 26 having a plurality of evenly spaced helical cutter blades 27 integrally affixed to the outer surface of the frusto-conical base 26 and continuing around the outer end thereof. The cutting edges of the blades are constructed to close tolerances with respect to their relationship to the inner surface of shear tube 20 so as to provide a constant shearing action with the shear tube.

The outer end of the frusto-conical base is provided with an axial pivot 23 which is suitably journalled in bearing 29 aflixed to the center of the perforated end wall 30 which encloses the outer end of shear tube 20. The other end of base 26 is provided with an axial shaft 31 which is coupled to drive shaft 32 of motor 11 by a suitable coupling means 33. Instead of employing a frusto-conical base as a base for the helical cutting blades a plurality of spaced spiders or the like can be employed as blade mounts or the blades can be attached directly to an axle.

To facilitate the removal of any accumulation of sheared hair from within the interior of the cutter as-' sembly 19 the cutting blades are eliminated from the end of cutter base 26 adjacent the face of rotating collar 14. Shear tube 20 is also provided with slotted openings 34 in this area in order to provide a positive cleaning action. In addition the use of retaining ring 22 as a means for holding shear tube 20 in place permits the easy removal of the tube for additional cleaning when necessary. Shear tube 20 is thin enough and is provided with a sufficient number of perforations 35 of a size sufficient to permit the free entry of beard stubble such that a close cropping of the beard is effected by the cooperative relative movement of the rapidly rotating cutter head 25 in cooperation with the freely rotatable shear head 20. Although in the illustrative embodiment perforations of circular cross section are employed, it is intended that various other geometrical shapes such as triangular, slotted, etc. can be utilized to permit the entry of the beard stubble for shearing. Obviously the perforations of the shear tube have to be sufficiently small to hold the beard stubble during the shearing action. It has been found, for example, that a hole size produced by the use of a No. 60 drill is satisfactory. The cutter head 25 can be provided with one or more blade elements 27. It is preferred, however, to utilize four blades for efiicient operation as shown. However, other numbers can be employed depending upon the requirements of the designer.

The conical shaped cutting head shown in FIGURE 1 is preferred because it increases the versatility of dry shavers on which it is used. In addition to its use in the shaving of facial areas its shape, the conical head is especially adaptable in removing the hair from the axilla area because the conical shape of the head permits the cutting head to be manipulated within the irregular shaped areas of the underarm.

In FIGURE 6 is shown another embodiment wherein a cutting head having a circular, transverse cross section is employed. In this instance the cutter assembly 39 comprising a shear tube 44 and cutter head 52 is pivotally mounted to the motor housing. This arrangement permits the cutter head to be operated at various angles up to about angular displacement during use in order to facilitate the shaving operation. In this embodiment a fragmentary view is shown of motor housing 40. Motor housing .40 is provided with a necked-down portion having a threaded neck 41. A bellows type sleeve 42 fabricated from a material which is sufficiently rigid to resist deformation from the weight of the cutter head alone but which will yield under pressure applied during the use is fitted to threaded neck 41 by means of an internally threaded collar portion 43 of bellows 42. Preferably the band of the threaded elements is selected so that the bellows will not be detached by the rotation of the cutter head. The other end of sleeve 42 employs a rotating assembly such as that utilized in FIGURE 1 to permit the free rotation of shear tube 44. In this instance shear tube 44 employs a band 45 encircling the free end thereof and secured thereto which is provided with an inner groove 46. An opposed peripheral groove 47 is also provided in the outer face adjacent the free end of flexible sleeve 42. A locking ring 50 couples shear tube 44 to flexible sleeve 42 and an expanding metal clip 51 mounted within peripheral groove 46 functions as a bearing surface to permit the free and smooth rotation of shear tube 44. The-cutter head 52 employs a cylindrical base 53 upon the side and end of which is helically mounted a plurality of cutting blades 54. Base 53 is suitably journalled in the perforated end wall 55 of shear tube 44 and employs the pivot bearing as hereinbefore described. A suitable flexible coupling means 56 is used to couple base shaft 57 to motor drive shaft 58. Although in the foregoing illustrative examples dry shavers employing single cutting heads are employed it is also apparent that multi-cutting head dry shavers utilizing theprinciples ofthis invention can be employed. Sucha dry shaver is illustrated in FIGURES 7, 8, and 9. In this embodiment three cutting elements are combined in asingle shaving head as shown. In FIGURE 7 motor housing 6i} has a neck portion 61 provided with an internal shoulder 62. An intermediate mounting plate 64 having an annular ring 65 is fitted within shoulder 62 of housing-60. A cutter head frame 66 has a flanged end 67 which mates with the flanged end of mounting plate 64 and is held in place by means of threaded fasteners 68 which connect the cutter head frame 66 and mounting plate 64 to motor housing 60 by means of a flanged mounting area provided on housing 60. The flanged end 67 and end 69 of cutter head frame 66 are provided with circular recesses in which are journalled shear tubes 71 which are freely rotatably mounted therein. Axially mounted within shear tubes 71 are cutting heads 72 which consist of a cylindrical base 73 having a plurality of cutting blades 74 helically mounted thereon. The rotation of these cutting heads is effected by motor 75 which is coupled directly to the central cutting head by means of shaft 76 and coupling 77. Pinions 78, 79, and 80 are integrally fitted to the ends of rotating bases 73. The shaft of the centralcutting head 74 is connected directly to coupling 77 and upon being driven by motor 75 effects the rotation of pinions 78 and 80 by means of intermediate pinions 81 and 82 rotatably journalled within end wall 67 of cutter head frame 66. V

- Although an electric motor is illustrated in the foregoing embodiment as the drive means, it is apparent that other types of motors such as spring-driven clock motors can be utilized if desired to effect the rotation of the cutter heads. Electric motors, however, are preferred. 7 Generally the action of the cutter blade employed in the instant invention will permit the use of a motor having a slower r.p.m. output than is necessary for a reciprocating type of cutter head. It has been found, for example, that motor speeds of 18,000 r.p.m. are suflicient to effect the desired operation of the cutter. In certain designs employing the instant invention wherein the cutter is journalled directly in the end wall of the shear plate, the shear plate that surrounds the cutter will begin to spin rapidly in the direction ofthe rotating cutter. However, a rotating coupling for connecting the shear tube in the assembly can be employed which provides a suflicient resistance such that this free rotation can be avoided. The rotating direction of the cutter is immaterial and, the cutter blades if properly designed can operate clock-wise or counter clock-wise. The cutting edge of the cutter blade should be extremely sharp. One of the advantages of the conical type of cutter arrangement is that the tapered cutting edges will tend to be self-honing during use. Although the illustrated embodiments show theuse of a motor housing which depends laterally from the cut.- ting head it is apparent that otherdesigns for dry shavers employing the instant invention can be utilized in which the motor housing can be constructed such that the axis of the cutting. edge can lay transverse to the axis of the motor housing. It is preferred, however, to employ r0.- tating cutters which have the axes lying coextensive with the longitudinal axis of the motor because the direct connection between the motor and the cutter is the preferred type of drive.

It is apparent from the foregoing description of this invention that various modifications can be made Without departing from the scope of the invention as illustrated by the above described specific embodiments. The cooperative eifect of the freely rotatable shear tube and the cutting action produced by the helical cutting blades provides a more efiicient and smoother operation than can be produced by conventional dry shavers described in the prior art. Accordingly I claim as my invention:

1. A dry shaver which comprises a housing, a motor within said housing, a fixed flexible sleeve connected at one end to said housing, a cutter assembly connected to the other end of said sleeve, whereby said assembly is hingedly mounted on said housing, said cutter assembly comprising a freely rotatable perforated shear tube journalled on said sleeve and a rotatable cutter head comprising at least one helical cutting blade mounted on a longitudinal axis within said tube coaxial therewith in shearing relationship, and flexible coupling means operatively connecting said cutter head and said motor to rotate said cutter head. 7

2. A dry shaver which comprises a housing, a motor mounted within said housing, a fixed flexible sleeve connected at one end to said housing, a cutter assembly connected to the other end of said sleeve, whereby said assembly is hingedly mounted on said housing, said cutter assembly comprising a freely rotatable perforated shear tube journalled on said sleeve substantially coaxial with said motor, a rotatable cutter head comprising at least one helical cutting blade mounted on a longitudinal axis within said tube coaxial therewith in shearing relationship, flexible coupling means operatively connecting said cutter head and said motor to rotate said cutter head.

3. A dry shaver which comprises a housing, a motor mounted within said housing, a fixed flexible sleeve connected at one end to said housing, a cutter assembly connected to the other end of said sleeve, whereby said assembly is hingedly mounted on said housing, said cutter assembly comprising a freely rotatable perforated frustoconical shear tube journalled on said sleeve coaxial with said motor, a rotatable cutter head comprising a plurality of helical cutting blades mounted on a frusto-conical base similar to said tube within said tube coaxial therewith in shearing relationship, flexible coupling means operatively connecting said cutter head and said motor in a direct drive between said cutter and said motor to rotate said cutter head in one direction.

4. A dry shaver which comprises a housing, a motor within said housing, a fixed flexible sleeve connected at one end to said housing, a cutter assembly connected to the other end of said housing, said cutter assembly comprising a freely rotatable perforated frusto-conical shear tube journalled on said sleeve coaxial with said motor, said shear tube having a perforation pattern substantially throughout its extent and having a perforated concave apex having an imperforate central portion, a retatable cutter head journalled at one end in said imperforate central portion and comprising a plurality of helical cutting blades mounted on a frusto-conical base similar to and within said tube and coaxial therewith, said cutting blades being substantially coextensive with said perforation pattern in shearing relationship, flexible coupling means operatively connecting the other end of said cutter head and said motor in direct drive between said cutter head and said motor to rotate said cutter head in one direction.

References Cited in the file of this patent UNITED STATES PATENTS 1,420,943 Philp June 27, 1922 2,055,517 Branstetter Sept. 29, 1936 2,216,672 McGall Oct. 1, 1940 2,216,673 McGall Oct. 1, 1940 2,218,312 Gardner Oct. 15, 1940 2,243,441 Russell May 27, 1941 2,245,917 Hill June 17, 1941 2,321,932 Nyhagen June 15, 1943 2,332,498 Burks Oct. 26, 1943 2,333,437 Olschewski Nov. 2, 1943 2,595,693 Norwood May 6, 1952 Kusznir Feb. 12, 1957 

